The objective of the proposed research is to understand the regulation of two genes whose products are essential for normal development and longevity in Drosophila melanogaster. In addition, mutations in one of these two genes which prematurely terminate translation will be induced and characterized. Suppressors of these mutations will then be induced and analyzed genetically. The two genes code for two enzymes, Alphaglycerophosphate dehydrogenase and Alphaglycerophosphate oxidase, which act in concert in the thoracic flight muscle of Dipteran insects to provide the energy source necessary for sustained flight. Mutations in the gene for the dehydrogenase result in an inability to fly and a premature aging syndrome. Putative regulatory and nonsense mutations in this gene have been induced and identified. The gene will be cloned from wild type strains, and the exact nature and location of each of these mutations will be determined by direct sequencing. It is expected that this information on the putative regulatory mutations will define regions of the locus important for normal regulation. These regions will be subcloned into expression vectors and their functional role will be assessed by homologous transformation. Additional nonsense mutations will be generated in vitro in the cloned gene and characterized by sequencing. The ability of heterologous suppressor genes to suppress the nonsense mutations will be measured in transformation experiments, and Drosophila suppressor mutations will be induced with mutagens in vivo and mapped within the genome. A major aim of this proposal is to extend these investigations to the gene for Alphaglycerophosphate oxidase. The structural gene has now been mapped and null mutants will be induced and studied for their effects on development and mitochondrial structure. The gene will be cloned and mutations which affect its regulation will be characterized. Sequences from regulatory regions of the two genes which are homologous and functionally important in coordinate control will be identified.